It has been recognized that packages for medicinal and other materials should preferably be resistant for removal by children. In one child resistant package shown in U.S. Pat. No. 4,059,198, the package comprises a cylindrical plastic body which has circumferentially spaced radially extending projections on the upper end thereof which have downwardly facing notches therein. The closure associated with the container comprises a one-piece plastic body having a top panel and a depending annular skirt with circumferentially spaced lugs extending radially inwardly for engagement with the notches. The closure includes a one-piece liner comprising a disc member which engages the upper rim of the container and includes a downwardly depending plug member which provides a vapor-tight seal with the inside surface of the container. The liner also serves as a spring between the closure and the container to bias the closure lugs into engagement with the projections on the container.
In some circumstances, it has been found that such a closure may be difficult to remove from the container even though released from locking position because of the tendency of the plug portion of the liner to resist removal of the closure.
Accordingly, among the objectives of the present invention are to provide a child resistant package of the type wherein sealing engagement is provided with the inner surface of the container and the closure can be more readily removed; which feature of ready removability is achieved in a simple and inexpensive manner.
In accordance with the invention, the child resistant package comprises an open-mouth plastic container and a closure. The closure has a plurality of circumferentially spaced projections extending radially outwardly adjacent the open end thereof, each projection having a shoulder facing downwardly in one circumferential direction. A closure has a top panel and an annular skirt depending from the periphery of the top panel and a plurality of radially inwardly extending and circumferentially spaced locking lugs on the inner surface of the skirt. The locking lugs are adapted to engage the shoulders in the projections on the container. The closure has a liner sealingly engaging the open end of the container and extending downwardly into sealing engagement with the inner surface of the upper open end of the container. The closure has at least one cam lug positioned on the inner surface of said skirt such that it is positioned between projections when the closure is on the container and the locking lugs are in engagement with the projections. The cam lug has an inclined surface operable when an axial force is applied to the closure and the closure is rotated in a direction to disengage the locking lugs from the projections so that continued rotation of the closure will cam the closure axially upwardly disengaging the closure from the container.